Question

Answer the following questions using the sequence given below.

Non-template DNA 5’ – ATG CGT TCG TTA TGG CTG CTT – 3’

1. Provide sequence of template DNA

2. Provide sequence of mRNA

3. Provide sequence of tRNA anticodon for the 3rd triplet

4. Provide the sequence of the amino acid encoded by the mRNA

5. What is the effect on the amino acid sequence as a result of each of the following mutations?

substitution of T for G at position 8

addition of T between positions 8 and 9

deletion of C at position 15

substitution of T for C at position 18

deletion of GAC at positions 16-18

Which of the mutations above produces the greatest change in the amino acid sequence?

Answer 1

The 5'-3' strand is known as the Non-template strand or Non-coding strand and the 3'-5' strand is known as the template strand or coding strand.

Non-template DNA: 5’ – ATG CGT TCG TTA TGG CTG CTT – 3’

1. Template DNA: 3'-TAC GCA AGC AAT ACC GAC GAA -5'

2. The mRNA is transcribed from the template strand DNA,so the

mRNA : 5'- AUG CGU UCG UUA UGG CUG CUU -3'

3. The tRNA sequence synthesis from the mRNA is called the translation.

the anticodon sequence for tRNA: UAC GCA AGC AAU ACC GAC GAA

So the tRNA anticodon sequence of the 3rd triplet is- AGC

4. The amino acid sequence encoded by the mRNA is- Met-Arg-Ser-Leu-Trp-Leu-Leu

5. If a base substituation takes place

• at the 8 position of template strand T in place of the G,then the

DNA sequence of the triplet would be: ATC and the mRNA sequence would be: UAG

then the amino acid sequence would be:  Met-Arg-(Stop Codon).

• Addition of T between the position 8 & 9,then the DNA template would be: TAC GCA AGT CAA TAC CGA CGA A

The mRNA sequence is: AUG CGU UCA GUU AUG GCU GCU U

The amino acid sequence is: Met-Arg-Ser-Val-Met-Ala-Ala.

• If deletion of C takes place at the position 15 then the codon triplet would be- A

Then the mRNA seuence would be: Met-Arg-Ser-Leu-Leu-Leu

• Substitution of T for C at the position 18. Then the DNA triplet codon would be: GAT, then the mRNA sequence would be: CUA

Then the mRNA sequencee would be: Met-Arg-Ser-Leu-Trp-Leu-Leu

• If the GAC is removed from the 16-18 position then the DNA sequeence would be:

TAC GCA AGC AAT ACC GAA

The mRNA sequence would be: AUG CGU UCG UUA UGG CUU

The amino acid sequence would be: Met-Arg-Ser-Leu-Trp-Leu.

• The first mutation substitution of T for G at position 8 is the greatest mutation as the synthesis of the amino acids stops there because the change in the base pair causes to make a stop codon and the amino acid synthesis stops there.